1. Field of the Invention
The present invention relates to an apparatus for assembling vehicle bodies and more particularly to an apparatus for installing vehicle doors on vehicle bodies. More specifically, the present invention pertains to an apparatus in which door assemblies transported to an assembling station are picked up one and located to an appropriate position by means of an assembling robot with respect to a vehicle body on which the door assembly is to be installed so that door installing operation is facilitated.
2. Description of the Prior Art
In Japanese patent publication No. 57-48334, there is disclosed a vehicle door installing apparatus for installing a vehicle side door on a vehicle body which is being transported along an assembling line. The door installing apparatus proposed in this patent publication includes a door locating robot which is adapted to move along the assembling line between a door picking up station and a door installing station. The locating robot picks up a door in the picking up station and moves to the door installing station to locate the door in an appropriate position with respect to the vehicle body in the door installing station. Alternatively, the robot may be moved in a synchronized relationship with the vehicle body which is being transported on the assembling line so that it can locate the door which is carried by the robot with respect to the vehicle body to be installed on the vehicle body. After the door is assembled on the vehicle body, the robot is moved to the door pick up station to repeat the same operation. The U.S. Pat. No. 4,627,158 issued to S. Mitoh proposes to provide the robot with a door locating device for positioning the vehicle door in an accurate position with respect to the robot arm so that the door to be installed on the vehicle body can be located with respect to the vehicle body by simply controlling the robot.
The door installing apparatus as disclosed by the Japanese patent publication is advantageous in that the door to be installed on the vehicle body is automatically carried to the installing station by the robot so that it does not require any man power for transporting the door to the installing station. It should however be noted that the proposed apparatus has a disadvantage in that the robot has to be moved between the installing station and the door picking up position so that no installing operation can be carried out when the robot is being moved. In case of a four door type vehicle which has two side doors on each side, it therefore becomes necessary to have the vehicle body wait in the installing station after one of the side doors is installed until the robot moves to the door pick up position to pick up the second door and comes back to the installing station producing problems of loss of time.